linux/fs/lockd/clntproc.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * linux/fs/lockd/clntproc.c
   4 *
   5 * RPC procedures for the client side NLM implementation
   6 *
   7 * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
   8 */
   9
  10#include <linux/module.h>
  11#include <linux/slab.h>
  12#include <linux/types.h>
  13#include <linux/errno.h>
  14#include <linux/fs.h>
  15#include <linux/nfs_fs.h>
  16#include <linux/utsname.h>
  17#include <linux/freezer.h>
  18#include <linux/sunrpc/clnt.h>
  19#include <linux/sunrpc/svc.h>
  20#include <linux/lockd/lockd.h>
  21
  22#define NLMDBG_FACILITY         NLMDBG_CLIENT
  23#define NLMCLNT_GRACE_WAIT      (5*HZ)
  24#define NLMCLNT_POLL_TIMEOUT    (30*HZ)
  25#define NLMCLNT_MAX_RETRIES     3
  26
  27static int      nlmclnt_test(struct nlm_rqst *, struct file_lock *);
  28static int      nlmclnt_lock(struct nlm_rqst *, struct file_lock *);
  29static int      nlmclnt_unlock(struct nlm_rqst *, struct file_lock *);
  30static int      nlm_stat_to_errno(__be32 stat);
  31static void     nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host);
  32static int      nlmclnt_cancel(struct nlm_host *, int , struct file_lock *);
  33
  34static const struct rpc_call_ops nlmclnt_unlock_ops;
  35static const struct rpc_call_ops nlmclnt_cancel_ops;
  36
  37/*
  38 * Cookie counter for NLM requests
  39 */
  40static atomic_t nlm_cookie = ATOMIC_INIT(0x1234);
  41
  42void nlmclnt_next_cookie(struct nlm_cookie *c)
  43{
  44        u32     cookie = atomic_inc_return(&nlm_cookie);
  45
  46        memcpy(c->data, &cookie, 4);
  47        c->len=4;
  48}
  49
  50static struct nlm_lockowner *
  51nlmclnt_get_lockowner(struct nlm_lockowner *lockowner)
  52{
  53        refcount_inc(&lockowner->count);
  54        return lockowner;
  55}
  56
  57static void nlmclnt_put_lockowner(struct nlm_lockowner *lockowner)
  58{
  59        if (!refcount_dec_and_lock(&lockowner->count, &lockowner->host->h_lock))
  60                return;
  61        list_del(&lockowner->list);
  62        spin_unlock(&lockowner->host->h_lock);
  63        nlmclnt_release_host(lockowner->host);
  64        kfree(lockowner);
  65}
  66
  67static inline int nlm_pidbusy(struct nlm_host *host, uint32_t pid)
  68{
  69        struct nlm_lockowner *lockowner;
  70        list_for_each_entry(lockowner, &host->h_lockowners, list) {
  71                if (lockowner->pid == pid)
  72                        return -EBUSY;
  73        }
  74        return 0;
  75}
  76
  77static inline uint32_t __nlm_alloc_pid(struct nlm_host *host)
  78{
  79        uint32_t res;
  80        do {
  81                res = host->h_pidcount++;
  82        } while (nlm_pidbusy(host, res) < 0);
  83        return res;
  84}
  85
  86static struct nlm_lockowner *__nlmclnt_find_lockowner(struct nlm_host *host, fl_owner_t owner)
  87{
  88        struct nlm_lockowner *lockowner;
  89        list_for_each_entry(lockowner, &host->h_lockowners, list) {
  90                if (lockowner->owner != owner)
  91                        continue;
  92                return nlmclnt_get_lockowner(lockowner);
  93        }
  94        return NULL;
  95}
  96
  97static struct nlm_lockowner *nlmclnt_find_lockowner(struct nlm_host *host, fl_owner_t owner)
  98{
  99        struct nlm_lockowner *res, *new = NULL;
 100
 101        spin_lock(&host->h_lock);
 102        res = __nlmclnt_find_lockowner(host, owner);
 103        if (res == NULL) {
 104                spin_unlock(&host->h_lock);
 105                new = kmalloc(sizeof(*new), GFP_KERNEL);
 106                spin_lock(&host->h_lock);
 107                res = __nlmclnt_find_lockowner(host, owner);
 108                if (res == NULL && new != NULL) {
 109                        res = new;
 110                        refcount_set(&new->count, 1);
 111                        new->owner = owner;
 112                        new->pid = __nlm_alloc_pid(host);
 113                        new->host = nlm_get_host(host);
 114                        list_add(&new->list, &host->h_lockowners);
 115                        new = NULL;
 116                }
 117        }
 118        spin_unlock(&host->h_lock);
 119        kfree(new);
 120        return res;
 121}
 122
 123/*
 124 * Initialize arguments for TEST/LOCK/UNLOCK/CANCEL calls
 125 */
 126static void nlmclnt_setlockargs(struct nlm_rqst *req, struct file_lock *fl)
 127{
 128        struct nlm_args *argp = &req->a_args;
 129        struct nlm_lock *lock = &argp->lock;
 130        char *nodename = req->a_host->h_rpcclnt->cl_nodename;
 131
 132        nlmclnt_next_cookie(&argp->cookie);
 133        memcpy(&lock->fh, NFS_FH(locks_inode(fl->fl_file)), sizeof(struct nfs_fh));
 134        lock->caller  = nodename;
 135        lock->oh.data = req->a_owner;
 136        lock->oh.len  = snprintf(req->a_owner, sizeof(req->a_owner), "%u@%s",
 137                                (unsigned int)fl->fl_u.nfs_fl.owner->pid,
 138                                nodename);
 139        lock->svid = fl->fl_u.nfs_fl.owner->pid;
 140        lock->fl.fl_start = fl->fl_start;
 141        lock->fl.fl_end = fl->fl_end;
 142        lock->fl.fl_type = fl->fl_type;
 143}
 144
 145static void nlmclnt_release_lockargs(struct nlm_rqst *req)
 146{
 147        WARN_ON_ONCE(req->a_args.lock.fl.fl_ops != NULL);
 148}
 149
 150/**
 151 * nlmclnt_proc - Perform a single client-side lock request
 152 * @host: address of a valid nlm_host context representing the NLM server
 153 * @cmd: fcntl-style file lock operation to perform
 154 * @fl: address of arguments for the lock operation
 155 * @data: address of data to be sent to callback operations
 156 *
 157 */
 158int nlmclnt_proc(struct nlm_host *host, int cmd, struct file_lock *fl, void *data)
 159{
 160        struct nlm_rqst         *call;
 161        int                     status;
 162        const struct nlmclnt_operations *nlmclnt_ops = host->h_nlmclnt_ops;
 163
 164        call = nlm_alloc_call(host);
 165        if (call == NULL)
 166                return -ENOMEM;
 167
 168        if (nlmclnt_ops && nlmclnt_ops->nlmclnt_alloc_call)
 169                nlmclnt_ops->nlmclnt_alloc_call(data);
 170
 171        nlmclnt_locks_init_private(fl, host);
 172        if (!fl->fl_u.nfs_fl.owner) {
 173                /* lockowner allocation has failed */
 174                nlmclnt_release_call(call);
 175                return -ENOMEM;
 176        }
 177        /* Set up the argument struct */
 178        nlmclnt_setlockargs(call, fl);
 179        call->a_callback_data = data;
 180
 181        if (IS_SETLK(cmd) || IS_SETLKW(cmd)) {
 182                if (fl->fl_type != F_UNLCK) {
 183                        call->a_args.block = IS_SETLKW(cmd) ? 1 : 0;
 184                        status = nlmclnt_lock(call, fl);
 185                } else
 186                        status = nlmclnt_unlock(call, fl);
 187        } else if (IS_GETLK(cmd))
 188                status = nlmclnt_test(call, fl);
 189        else
 190                status = -EINVAL;
 191        fl->fl_ops->fl_release_private(fl);
 192        fl->fl_ops = NULL;
 193
 194        dprintk("lockd: clnt proc returns %d\n", status);
 195        return status;
 196}
 197EXPORT_SYMBOL_GPL(nlmclnt_proc);
 198
 199/*
 200 * Allocate an NLM RPC call struct
 201 */
 202struct nlm_rqst *nlm_alloc_call(struct nlm_host *host)
 203{
 204        struct nlm_rqst *call;
 205
 206        for(;;) {
 207                call = kzalloc(sizeof(*call), GFP_KERNEL);
 208                if (call != NULL) {
 209                        refcount_set(&call->a_count, 1);
 210                        locks_init_lock(&call->a_args.lock.fl);
 211                        locks_init_lock(&call->a_res.lock.fl);
 212                        call->a_host = nlm_get_host(host);
 213                        return call;
 214                }
 215                if (signalled())
 216                        break;
 217                printk("nlm_alloc_call: failed, waiting for memory\n");
 218                schedule_timeout_interruptible(5*HZ);
 219        }
 220        return NULL;
 221}
 222
 223void nlmclnt_release_call(struct nlm_rqst *call)
 224{
 225        const struct nlmclnt_operations *nlmclnt_ops = call->a_host->h_nlmclnt_ops;
 226
 227        if (!refcount_dec_and_test(&call->a_count))
 228                return;
 229        if (nlmclnt_ops && nlmclnt_ops->nlmclnt_release_call)
 230                nlmclnt_ops->nlmclnt_release_call(call->a_callback_data);
 231        nlmclnt_release_host(call->a_host);
 232        nlmclnt_release_lockargs(call);
 233        kfree(call);
 234}
 235
 236static void nlmclnt_rpc_release(void *data)
 237{
 238        nlmclnt_release_call(data);
 239}
 240
 241static int nlm_wait_on_grace(wait_queue_head_t *queue)
 242{
 243        DEFINE_WAIT(wait);
 244        int status = -EINTR;
 245
 246        prepare_to_wait(queue, &wait, TASK_INTERRUPTIBLE);
 247        if (!signalled ()) {
 248                schedule_timeout(NLMCLNT_GRACE_WAIT);
 249                try_to_freeze();
 250                if (!signalled ())
 251                        status = 0;
 252        }
 253        finish_wait(queue, &wait);
 254        return status;
 255}
 256
 257/*
 258 * Generic NLM call
 259 */
 260static int
 261nlmclnt_call(const struct cred *cred, struct nlm_rqst *req, u32 proc)
 262{
 263        struct nlm_host *host = req->a_host;
 264        struct rpc_clnt *clnt;
 265        struct nlm_args *argp = &req->a_args;
 266        struct nlm_res  *resp = &req->a_res;
 267        struct rpc_message msg = {
 268                .rpc_argp       = argp,
 269                .rpc_resp       = resp,
 270                .rpc_cred       = cred,
 271        };
 272        int             status;
 273
 274        dprintk("lockd: call procedure %d on %s\n",
 275                        (int)proc, host->h_name);
 276
 277        do {
 278                if (host->h_reclaiming && !argp->reclaim)
 279                        goto in_grace_period;
 280
 281                /* If we have no RPC client yet, create one. */
 282                if ((clnt = nlm_bind_host(host)) == NULL)
 283                        return -ENOLCK;
 284                msg.rpc_proc = &clnt->cl_procinfo[proc];
 285
 286                /* Perform the RPC call. If an error occurs, try again */
 287                if ((status = rpc_call_sync(clnt, &msg, 0)) < 0) {
 288                        dprintk("lockd: rpc_call returned error %d\n", -status);
 289                        switch (status) {
 290                        case -EPROTONOSUPPORT:
 291                                status = -EINVAL;
 292                                break;
 293                        case -ECONNREFUSED:
 294                        case -ETIMEDOUT:
 295                        case -ENOTCONN:
 296                                nlm_rebind_host(host);
 297                                status = -EAGAIN;
 298                                break;
 299                        case -ERESTARTSYS:
 300                                return signalled () ? -EINTR : status;
 301                        default:
 302                                break;
 303                        }
 304                        break;
 305                } else
 306                if (resp->status == nlm_lck_denied_grace_period) {
 307                        dprintk("lockd: server in grace period\n");
 308                        if (argp->reclaim) {
 309                                printk(KERN_WARNING
 310                                     "lockd: spurious grace period reject?!\n");
 311                                return -ENOLCK;
 312                        }
 313                } else {
 314                        if (!argp->reclaim) {
 315                                /* We appear to be out of the grace period */
 316                                wake_up_all(&host->h_gracewait);
 317                        }
 318                        dprintk("lockd: server returns status %d\n",
 319                                ntohl(resp->status));
 320                        return 0;       /* Okay, call complete */
 321                }
 322
 323in_grace_period:
 324                /*
 325                 * The server has rebooted and appears to be in the grace
 326                 * period during which locks are only allowed to be
 327                 * reclaimed.
 328                 * We can only back off and try again later.
 329                 */
 330                status = nlm_wait_on_grace(&host->h_gracewait);
 331        } while (status == 0);
 332
 333        return status;
 334}
 335
 336/*
 337 * Generic NLM call, async version.
 338 */
 339static struct rpc_task *__nlm_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
 340{
 341        struct nlm_host *host = req->a_host;
 342        struct rpc_clnt *clnt;
 343        struct rpc_task_setup task_setup_data = {
 344                .rpc_message = msg,
 345                .callback_ops = tk_ops,
 346                .callback_data = req,
 347                .flags = RPC_TASK_ASYNC,
 348        };
 349
 350        dprintk("lockd: call procedure %d on %s (async)\n",
 351                        (int)proc, host->h_name);
 352
 353        /* If we have no RPC client yet, create one. */
 354        clnt = nlm_bind_host(host);
 355        if (clnt == NULL)
 356                goto out_err;
 357        msg->rpc_proc = &clnt->cl_procinfo[proc];
 358        task_setup_data.rpc_client = clnt;
 359
 360        /* bootstrap and kick off the async RPC call */
 361        return rpc_run_task(&task_setup_data);
 362out_err:
 363        tk_ops->rpc_release(req);
 364        return ERR_PTR(-ENOLCK);
 365}
 366
 367static int nlm_do_async_call(struct nlm_rqst *req, u32 proc, struct rpc_message *msg, const struct rpc_call_ops *tk_ops)
 368{
 369        struct rpc_task *task;
 370
 371        task = __nlm_async_call(req, proc, msg, tk_ops);
 372        if (IS_ERR(task))
 373                return PTR_ERR(task);
 374        rpc_put_task(task);
 375        return 0;
 376}
 377
 378/*
 379 * NLM asynchronous call.
 380 */
 381int nlm_async_call(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 382{
 383        struct rpc_message msg = {
 384                .rpc_argp       = &req->a_args,
 385                .rpc_resp       = &req->a_res,
 386        };
 387        return nlm_do_async_call(req, proc, &msg, tk_ops);
 388}
 389
 390int nlm_async_reply(struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 391{
 392        struct rpc_message msg = {
 393                .rpc_argp       = &req->a_res,
 394        };
 395        return nlm_do_async_call(req, proc, &msg, tk_ops);
 396}
 397
 398/*
 399 * NLM client asynchronous call.
 400 *
 401 * Note that although the calls are asynchronous, and are therefore
 402 *      guaranteed to complete, we still always attempt to wait for
 403 *      completion in order to be able to correctly track the lock
 404 *      state.
 405 */
 406static int nlmclnt_async_call(const struct cred *cred, struct nlm_rqst *req, u32 proc, const struct rpc_call_ops *tk_ops)
 407{
 408        struct rpc_message msg = {
 409                .rpc_argp       = &req->a_args,
 410                .rpc_resp       = &req->a_res,
 411                .rpc_cred       = cred,
 412        };
 413        struct rpc_task *task;
 414        int err;
 415
 416        task = __nlm_async_call(req, proc, &msg, tk_ops);
 417        if (IS_ERR(task))
 418                return PTR_ERR(task);
 419        err = rpc_wait_for_completion_task(task);
 420        rpc_put_task(task);
 421        return err;
 422}
 423
 424/*
 425 * TEST for the presence of a conflicting lock
 426 */
 427static int
 428nlmclnt_test(struct nlm_rqst *req, struct file_lock *fl)
 429{
 430        int     status;
 431
 432        status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_TEST);
 433        if (status < 0)
 434                goto out;
 435
 436        switch (req->a_res.status) {
 437                case nlm_granted:
 438                        fl->fl_type = F_UNLCK;
 439                        break;
 440                case nlm_lck_denied:
 441                        /*
 442                         * Report the conflicting lock back to the application.
 443                         */
 444                        fl->fl_start = req->a_res.lock.fl.fl_start;
 445                        fl->fl_end = req->a_res.lock.fl.fl_end;
 446                        fl->fl_type = req->a_res.lock.fl.fl_type;
 447                        fl->fl_pid = -req->a_res.lock.fl.fl_pid;
 448                        break;
 449                default:
 450                        status = nlm_stat_to_errno(req->a_res.status);
 451        }
 452out:
 453        nlmclnt_release_call(req);
 454        return status;
 455}
 456
 457static void nlmclnt_locks_copy_lock(struct file_lock *new, struct file_lock *fl)
 458{
 459        spin_lock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 460        new->fl_u.nfs_fl.state = fl->fl_u.nfs_fl.state;
 461        new->fl_u.nfs_fl.owner = nlmclnt_get_lockowner(fl->fl_u.nfs_fl.owner);
 462        list_add_tail(&new->fl_u.nfs_fl.list, &fl->fl_u.nfs_fl.owner->host->h_granted);
 463        spin_unlock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 464}
 465
 466static void nlmclnt_locks_release_private(struct file_lock *fl)
 467{
 468        spin_lock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 469        list_del(&fl->fl_u.nfs_fl.list);
 470        spin_unlock(&fl->fl_u.nfs_fl.owner->host->h_lock);
 471        nlmclnt_put_lockowner(fl->fl_u.nfs_fl.owner);
 472}
 473
 474static const struct file_lock_operations nlmclnt_lock_ops = {
 475        .fl_copy_lock = nlmclnt_locks_copy_lock,
 476        .fl_release_private = nlmclnt_locks_release_private,
 477};
 478
 479static void nlmclnt_locks_init_private(struct file_lock *fl, struct nlm_host *host)
 480{
 481        fl->fl_u.nfs_fl.state = 0;
 482        fl->fl_u.nfs_fl.owner = nlmclnt_find_lockowner(host, fl->fl_owner);
 483        INIT_LIST_HEAD(&fl->fl_u.nfs_fl.list);
 484        fl->fl_ops = &nlmclnt_lock_ops;
 485}
 486
 487static int do_vfs_lock(struct file_lock *fl)
 488{
 489        return locks_lock_file_wait(fl->fl_file, fl);
 490}
 491
 492/*
 493 * LOCK: Try to create a lock
 494 *
 495 *                      Programmer Harassment Alert
 496 *
 497 * When given a blocking lock request in a sync RPC call, the HPUX lockd
 498 * will faithfully return LCK_BLOCKED but never cares to notify us when
 499 * the lock could be granted. This way, our local process could hang
 500 * around forever waiting for the callback.
 501 *
 502 *  Solution A: Implement busy-waiting
 503 *  Solution B: Use the async version of the call (NLM_LOCK_{MSG,RES})
 504 *
 505 * For now I am implementing solution A, because I hate the idea of
 506 * re-implementing lockd for a third time in two months. The async
 507 * calls shouldn't be too hard to do, however.
 508 *
 509 * This is one of the lovely things about standards in the NFS area:
 510 * they're so soft and squishy you can't really blame HP for doing this.
 511 */
 512static int
 513nlmclnt_lock(struct nlm_rqst *req, struct file_lock *fl)
 514{
 515        const struct cred *cred = nfs_file_cred(fl->fl_file);
 516        struct nlm_host *host = req->a_host;
 517        struct nlm_res  *resp = &req->a_res;
 518        struct nlm_wait *block = NULL;
 519        unsigned char fl_flags = fl->fl_flags;
 520        unsigned char fl_type;
 521        int status = -ENOLCK;
 522
 523        if (nsm_monitor(host) < 0)
 524                goto out;
 525        req->a_args.state = nsm_local_state;
 526
 527        fl->fl_flags |= FL_ACCESS;
 528        status = do_vfs_lock(fl);
 529        fl->fl_flags = fl_flags;
 530        if (status < 0)
 531                goto out;
 532
 533        block = nlmclnt_prepare_block(host, fl);
 534again:
 535        /*
 536         * Initialise resp->status to a valid non-zero value,
 537         * since 0 == nlm_lck_granted
 538         */
 539        resp->status = nlm_lck_blocked;
 540        for(;;) {
 541                /* Reboot protection */
 542                fl->fl_u.nfs_fl.state = host->h_state;
 543                status = nlmclnt_call(cred, req, NLMPROC_LOCK);
 544                if (status < 0)
 545                        break;
 546                /* Did a reclaimer thread notify us of a server reboot? */
 547                if (resp->status ==  nlm_lck_denied_grace_period)
 548                        continue;
 549                if (resp->status != nlm_lck_blocked)
 550                        break;
 551                /* Wait on an NLM blocking lock */
 552                status = nlmclnt_block(block, req, NLMCLNT_POLL_TIMEOUT);
 553                if (status < 0)
 554                        break;
 555                if (resp->status != nlm_lck_blocked)
 556                        break;
 557        }
 558
 559        /* if we were interrupted while blocking, then cancel the lock request
 560         * and exit
 561         */
 562        if (resp->status == nlm_lck_blocked) {
 563                if (!req->a_args.block)
 564                        goto out_unlock;
 565                if (nlmclnt_cancel(host, req->a_args.block, fl) == 0)
 566                        goto out_unblock;
 567        }
 568
 569        if (resp->status == nlm_granted) {
 570                down_read(&host->h_rwsem);
 571                /* Check whether or not the server has rebooted */
 572                if (fl->fl_u.nfs_fl.state != host->h_state) {
 573                        up_read(&host->h_rwsem);
 574                        goto again;
 575                }
 576                /* Ensure the resulting lock will get added to granted list */
 577                fl->fl_flags |= FL_SLEEP;
 578                if (do_vfs_lock(fl) < 0)
 579                        printk(KERN_WARNING "%s: VFS is out of sync with lock manager!\n", __func__);
 580                up_read(&host->h_rwsem);
 581                fl->fl_flags = fl_flags;
 582                status = 0;
 583        }
 584        if (status < 0)
 585                goto out_unlock;
 586        /*
 587         * EAGAIN doesn't make sense for sleeping locks, and in some
 588         * cases NLM_LCK_DENIED is returned for a permanent error.  So
 589         * turn it into an ENOLCK.
 590         */
 591        if (resp->status == nlm_lck_denied && (fl_flags & FL_SLEEP))
 592                status = -ENOLCK;
 593        else
 594                status = nlm_stat_to_errno(resp->status);
 595out_unblock:
 596        nlmclnt_finish_block(block);
 597out:
 598        nlmclnt_release_call(req);
 599        return status;
 600out_unlock:
 601        /* Fatal error: ensure that we remove the lock altogether */
 602        dprintk("lockd: lock attempt ended in fatal error.\n"
 603                "       Attempting to unlock.\n");
 604        nlmclnt_finish_block(block);
 605        fl_type = fl->fl_type;
 606        fl->fl_type = F_UNLCK;
 607        down_read(&host->h_rwsem);
 608        do_vfs_lock(fl);
 609        up_read(&host->h_rwsem);
 610        fl->fl_type = fl_type;
 611        fl->fl_flags = fl_flags;
 612        nlmclnt_async_call(cred, req, NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
 613        return status;
 614}
 615
 616/*
 617 * RECLAIM: Try to reclaim a lock
 618 */
 619int
 620nlmclnt_reclaim(struct nlm_host *host, struct file_lock *fl,
 621                struct nlm_rqst *req)
 622{
 623        int             status;
 624
 625        memset(req, 0, sizeof(*req));
 626        locks_init_lock(&req->a_args.lock.fl);
 627        locks_init_lock(&req->a_res.lock.fl);
 628        req->a_host  = host;
 629
 630        /* Set up the argument struct */
 631        nlmclnt_setlockargs(req, fl);
 632        req->a_args.reclaim = 1;
 633
 634        status = nlmclnt_call(nfs_file_cred(fl->fl_file), req, NLMPROC_LOCK);
 635        if (status >= 0 && req->a_res.status == nlm_granted)
 636                return 0;
 637
 638        printk(KERN_WARNING "lockd: failed to reclaim lock for pid %d "
 639                                "(errno %d, status %d)\n", fl->fl_pid,
 640                                status, ntohl(req->a_res.status));
 641
 642        /*
 643         * FIXME: This is a serious failure. We can
 644         *
 645         *  a.  Ignore the problem
 646         *  b.  Send the owning process some signal (Linux doesn't have
 647         *      SIGLOST, though...)
 648         *  c.  Retry the operation
 649         *
 650         * Until someone comes up with a simple implementation
 651         * for b or c, I'll choose option a.
 652         */
 653
 654        return -ENOLCK;
 655}
 656
 657/*
 658 * UNLOCK: remove an existing lock
 659 */
 660static int
 661nlmclnt_unlock(struct nlm_rqst *req, struct file_lock *fl)
 662{
 663        struct nlm_host *host = req->a_host;
 664        struct nlm_res  *resp = &req->a_res;
 665        int status;
 666        unsigned char fl_flags = fl->fl_flags;
 667
 668        /*
 669         * Note: the server is supposed to either grant us the unlock
 670         * request, or to deny it with NLM_LCK_DENIED_GRACE_PERIOD. In either
 671         * case, we want to unlock.
 672         */
 673        fl->fl_flags |= FL_EXISTS;
 674        down_read(&host->h_rwsem);
 675        status = do_vfs_lock(fl);
 676        up_read(&host->h_rwsem);
 677        fl->fl_flags = fl_flags;
 678        if (status == -ENOENT) {
 679                status = 0;
 680                goto out;
 681        }
 682
 683        refcount_inc(&req->a_count);
 684        status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
 685                        NLMPROC_UNLOCK, &nlmclnt_unlock_ops);
 686        if (status < 0)
 687                goto out;
 688
 689        if (resp->status == nlm_granted)
 690                goto out;
 691
 692        if (resp->status != nlm_lck_denied_nolocks)
 693                printk("lockd: unexpected unlock status: %d\n",
 694                        ntohl(resp->status));
 695        /* What to do now? I'm out of my depth... */
 696        status = -ENOLCK;
 697out:
 698        nlmclnt_release_call(req);
 699        return status;
 700}
 701
 702static void nlmclnt_unlock_prepare(struct rpc_task *task, void *data)
 703{
 704        struct nlm_rqst *req = data;
 705        const struct nlmclnt_operations *nlmclnt_ops = req->a_host->h_nlmclnt_ops;
 706        bool defer_call = false;
 707
 708        if (nlmclnt_ops && nlmclnt_ops->nlmclnt_unlock_prepare)
 709                defer_call = nlmclnt_ops->nlmclnt_unlock_prepare(task, req->a_callback_data);
 710
 711        if (!defer_call)
 712                rpc_call_start(task);
 713}
 714
 715static void nlmclnt_unlock_callback(struct rpc_task *task, void *data)
 716{
 717        struct nlm_rqst *req = data;
 718        u32 status = ntohl(req->a_res.status);
 719
 720        if (RPC_SIGNALLED(task))
 721                goto die;
 722
 723        if (task->tk_status < 0) {
 724                dprintk("lockd: unlock failed (err = %d)\n", -task->tk_status);
 725                switch (task->tk_status) {
 726                case -EACCES:
 727                case -EIO:
 728                        goto die;
 729                default:
 730                        goto retry_rebind;
 731                }
 732        }
 733        if (status == NLM_LCK_DENIED_GRACE_PERIOD) {
 734                rpc_delay(task, NLMCLNT_GRACE_WAIT);
 735                goto retry_unlock;
 736        }
 737        if (status != NLM_LCK_GRANTED)
 738                printk(KERN_WARNING "lockd: unexpected unlock status: %d\n", status);
 739die:
 740        return;
 741 retry_rebind:
 742        nlm_rebind_host(req->a_host);
 743 retry_unlock:
 744        rpc_restart_call(task);
 745}
 746
 747static const struct rpc_call_ops nlmclnt_unlock_ops = {
 748        .rpc_call_prepare = nlmclnt_unlock_prepare,
 749        .rpc_call_done = nlmclnt_unlock_callback,
 750        .rpc_release = nlmclnt_rpc_release,
 751};
 752
 753/*
 754 * Cancel a blocked lock request.
 755 * We always use an async RPC call for this in order not to hang a
 756 * process that has been Ctrl-C'ed.
 757 */
 758static int nlmclnt_cancel(struct nlm_host *host, int block, struct file_lock *fl)
 759{
 760        struct nlm_rqst *req;
 761        int status;
 762
 763        dprintk("lockd: blocking lock attempt was interrupted by a signal.\n"
 764                "       Attempting to cancel lock.\n");
 765
 766        req = nlm_alloc_call(host);
 767        if (!req)
 768                return -ENOMEM;
 769        req->a_flags = RPC_TASK_ASYNC;
 770
 771        nlmclnt_setlockargs(req, fl);
 772        req->a_args.block = block;
 773
 774        refcount_inc(&req->a_count);
 775        status = nlmclnt_async_call(nfs_file_cred(fl->fl_file), req,
 776                        NLMPROC_CANCEL, &nlmclnt_cancel_ops);
 777        if (status == 0 && req->a_res.status == nlm_lck_denied)
 778                status = -ENOLCK;
 779        nlmclnt_release_call(req);
 780        return status;
 781}
 782
 783static void nlmclnt_cancel_callback(struct rpc_task *task, void *data)
 784{
 785        struct nlm_rqst *req = data;
 786        u32 status = ntohl(req->a_res.status);
 787
 788        if (RPC_SIGNALLED(task))
 789                goto die;
 790
 791        if (task->tk_status < 0) {
 792                dprintk("lockd: CANCEL call error %d, retrying.\n",
 793                                        task->tk_status);
 794                goto retry_cancel;
 795        }
 796
 797        dprintk("lockd: cancel status %u (task %u)\n",
 798                        status, task->tk_pid);
 799
 800        switch (status) {
 801        case NLM_LCK_GRANTED:
 802        case NLM_LCK_DENIED_GRACE_PERIOD:
 803        case NLM_LCK_DENIED:
 804                /* Everything's good */
 805                break;
 806        case NLM_LCK_DENIED_NOLOCKS:
 807                dprintk("lockd: CANCEL failed (server has no locks)\n");
 808                goto retry_cancel;
 809        default:
 810                printk(KERN_NOTICE "lockd: weird return %d for CANCEL call\n",
 811                        status);
 812        }
 813
 814die:
 815        return;
 816
 817retry_cancel:
 818        /* Don't ever retry more than 3 times */
 819        if (req->a_retries++ >= NLMCLNT_MAX_RETRIES)
 820                goto die;
 821        nlm_rebind_host(req->a_host);
 822        rpc_restart_call(task);
 823        rpc_delay(task, 30 * HZ);
 824}
 825
 826static const struct rpc_call_ops nlmclnt_cancel_ops = {
 827        .rpc_call_done = nlmclnt_cancel_callback,
 828        .rpc_release = nlmclnt_rpc_release,
 829};
 830
 831/*
 832 * Convert an NLM status code to a generic kernel errno
 833 */
 834static int
 835nlm_stat_to_errno(__be32 status)
 836{
 837        switch(ntohl(status)) {
 838        case NLM_LCK_GRANTED:
 839                return 0;
 840        case NLM_LCK_DENIED:
 841                return -EAGAIN;
 842        case NLM_LCK_DENIED_NOLOCKS:
 843        case NLM_LCK_DENIED_GRACE_PERIOD:
 844                return -ENOLCK;
 845        case NLM_LCK_BLOCKED:
 846                printk(KERN_NOTICE "lockd: unexpected status NLM_BLOCKED\n");
 847                return -ENOLCK;
 848#ifdef CONFIG_LOCKD_V4
 849        case NLM_DEADLCK:
 850                return -EDEADLK;
 851        case NLM_ROFS:
 852                return -EROFS;
 853        case NLM_STALE_FH:
 854                return -ESTALE;
 855        case NLM_FBIG:
 856                return -EOVERFLOW;
 857        case NLM_FAILED:
 858                return -ENOLCK;
 859#endif
 860        }
 861        printk(KERN_NOTICE "lockd: unexpected server status %d\n",
 862                 ntohl(status));
 863        return -ENOLCK;
 864}
 865